I see some experts only care about the sweep pattern on the valve tip. I see come adjust the rocker arm shaft, and pushrod length to get the rocker arm perpendicular to the spring retainer at one half valve lift, and then make sure the pattern on the valve tip is within .040" from the edge. With non-roller rockers, that perpendicular is measured from the rocker arm foot to valve tip contact, through the centerline of the rocker shaft, but with roller rockers, it's taken from the center of the roller rocker tip, through the center of the rocker shaft. Is this correct? If so, then I need to raise my rocker shaft .25". WTH? I also don't see how changing the pushrod length changes geometry, or is that just for Chevys where you adjust the rocker up and down also?